Retroreflective films are characterized by the ability to reflect incident light back toward an originating light source. Microsphere retroreflective sheeting, sometimes referred to as “beaded” retroreflective sheeting, typically comprises a monolayer of transparent microspheres supported by a binder. Light incident upon a front surface of the sheeting is retroreflected by the transparent microspheres and directed back toward the light source. A reflective material disposed behind the microspheres may be present to facilitate retroreflection. Beaded retroreflective sheeting may include a composite image that can provide a floating image that appears to be suspended above or below the sheeting. Beaded retroreflective sheeting may be used in traffic safety applications, such as for license plates, road signs, barricades, pavement markers and marking tape, as well as for personal safety applications including tape for clothing, headgear, vehicles and the like. Beaded retroreflective sheeting may be used to provide signage in graphic arts applications.
Beaded retroreflective sheeting is known for being able to reflect a large portion of incident light back towards an originating light source. Without a light source, however, beaded retroreflective sheeting can be difficult to see under some conditions.
Lightguides are used to facilitate distribution of light from a light source over an area much larger than the light source. Lightguides comprise optically transmissive materials and may have different forms such as slab, wedge, and pseudo-wedge forms. Most lightguides are designed to accept light at an edge surface and allow this light to propagate by total internal reflection between a back surface and an output surface, toward an opposing edge surface from which the light enters. Light is emitted uniformly from the output surface using extracting features that are positioned in various types of patterns on the output surface.